Regensburg 2016 – scientific programme

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O: Fachverband Oberflächenphysik

O 87: Metal Substrates: Structure, Epitaxy and Growth

O 87.1: Talk

Thursday, March 10, 2016, 15:00–15:15, S053

Zn on Au(111) - growth and alloy formation — •Konstantin M. Schüttler and R. Jürgen Behm — Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm, Germany

Methanol is a promising molecule for chemical energy storage, e.g. by use of H₂ from regenerative sources. Industrially, methanol is synthesized from syngas (CO/H₂) over Cu/ZnO catalysts. The synthesis of “Green Methanol” from CO₂/H₂ as “solar fuel” could make this synthetic fuel even independent of fossil energy carriers. It has recently been demonstrated that under reaction conditions the ZnO support of Cu/ZnO catalysts is partly reduced to Zn, forming a CuZn alloy which is proposed to contain the active site for this reaction. For the hydrogenation of CO₂, Au/ZnO is a highly promising catalyst, and in analogy to Cu/ZnO, reduction of ZnO and formation of bimetallic AuZn surfaces under reaction conditions is plausible.

In order to gain more insight into the formation and nature of active sites, we started to study the formation, structure and chemical properties of bimetallic Zn/Au(111) surfaces as structurally well-defined 2D model catalysts. Here we present first UHV-STM measurements on the growth and (surface) alloy formation of Zn on Au(111). Nucleation and 2D growth of Zn islands seems to start both at the elbow sites of the Au(111) herringbone reconstruction and at step edges. Equally possible, however, is that the observed structures are created by place exchange of Zn atoms into the first layer, which then act as trap sites for Zn and Au adatoms, where the latter result from Zn place exchange. This is tested in ongoing STM experiments.